Imaging devices are usually dedicated devices that offer single-type imaging capabilities, such as bright-field, dark-field, and frustrated total internal reflection imagers. Bright-field imagers are usually found in the consumer marketplace as the typical point-and-shoot camera or typical microscope. Dark-field imagers are useful in detecting surface roughness differences, which have specialized applications from consumer products to medical devices and military applications. Frustrated total internal reflection imagers are very sensitive to objects that are in direct contact with a smooth substrate, which makes them ideal imagers for applications like finger print readers.
For bright field, dark field, and frustrated total internal reflection imagers, a finite optical path is needed to create a quality image. Essentially, the entire imaging device needs a non-negligible thickness even if the sensor array can be made negligibly thin. Some applications have attempted to develop contact imaging systems that are based on large area thin film technology that does not use optical components and thus reduces or eliminates the need for a finite optical path. However, even these systems are limited to bright-field imaging and the resolution is directly proportional to how close a user can position an object to be imaged to the surface of the contact imaging system.
Accordingly, there remains a need for an improved optical system that is able to perform different modes of imaging, such as integrating bright-field, dark-field, and frustrated total internal reflection imaging, in an optical system by easily changing a design choice that does not require a finite optical path to produce quality images in any of the modes.